Walter



Patented Aug. 14, 1923.

UNITED STATES PATENT OFFICE.

WALTER O. SNELLING, OF ALLENTOWN, PENNSYLVANIA, ASSIGNOR TO TROJANPOWDEBCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

EXPLOSIVE.

No Drawing.

To all whom it may concern:

Be it known that I, WALTER O. SNELLING, a citizen of the United States,and resident of Allentown, Lehigh County, Pennsylvania, have inventedcertain Improvements in Explosives, of ,Which the following is aspecitication.

My invention relates to explosives for use in coal mining operations,and its object is to provide an explosive possessing the characteristicsrequisite for safe use in the presence of the inflammable gasesprevalent in coal mines, and possessing also the property of stabilitywhich is an essential of all practical commercial explosives.

Exhaustive experiments have shown that the flame temperature ofexplosives must be close to 2000 C. or lower to insure safety when theexplosives are employed in the presence of inflammable mine. gases. Ithas been one of the practices in attempting to reduce the normal flametemperatures of explosives to the safety point, to add to the explosivematerial salts such as sodium sulfate, magnesium sulfate, aluminiumsulfate and zinc sulfate, containing large amounts of Water ofcrystallization, the theory of the use of such salts being that acooling effect is produced upon the flame of explosion through theutilization of a portion of the heat energy in vaporizing the Water ofcrystallization and through the distribution of a further portion of theheat energy through the water vapor thus produced. This method hasproved successful to the extent that lower flame temperatures have beenobtained, but the product has proved unpractical as a commercialexplosive because of an inherent instability. These explosives have beenfound to be extremely liable to deterioration on storage. andparticularly so if they become somewhat wet.

I have discovered that the lack of stability of these explosives is dueto the fact that the temperature reducing agents hitherto employed havethe property of entering into chemical reaction with the nitrates, suchas the nitrates of ammonium, sodium, potassium. and barium, which form aconstituent of all commercial coal mining explosives.

I have further discovered that this tendency of thc temperature reducingagents to enter readily into reaction with the solublc alkali nitrateand alkali earth nitrates which are Application filed August 6, 1919.Serial N0. 315,674.

present in coal mining explosives, is due to z certain salts containingrelatively high percentages of water of crystallization which salts Ihave found will not react with the nitrates of sodium, ammonium,potassium and barium, and which accordingly may remain in admixture withan explosive for an indefinite period With no resultant deterioration.These salts are for practical purposes substantially insoluble in water,requiring fifty or more times their own weight of water to bring aboutsolution, and it is due to this property that they are able to withstandadmixture with alkali nitrates and alkali earth nitrates, withoutundergting reaction.

There are many materials adapted to the purposes of my invention. Asalready indicated, these materials should contain suitable amounts ofwater of crystallization or of constitution, and must be relativelyinsoluble in water: but also they should be relatively chemically inert,since there are many materials possessing the first named propertieswhich are nevertheless unsuitable for incorporation in an explosivebecause of their strongly acid or basic properties, or for otherreasons. As examples of some of the materials which I have found adaptedt my purpose, I may mention gypsum and ulcxite, and hydrous waterinsoluble minerals, cit-her natural or artificial, such as Brucite,Colemanite, Gibbsite, and Evansite. I have found also that in generalall chemically inert and water insoluble borates, sulfates, carbonatesand silicates, if they contain a suitable amount of water ofcrystallization, ma be applied to the purpose of mv invention, as wellas certain phosphates and arsenatcs of iron and other metals. I preferto use the borates of calcium and magnesium such as Colemanite andulexite, and such minerals as Brucite and gypsum, because of theirrelative availability; but in general, any material which is relativelychemically inert. which holds 10% or more of water of crystallization,and which rcquires for its solution not less than titty times its ownweight of water at a temperature of 20 is suitable.

in the formation of my explosive, a suitable amountol the temperaturereducing agent is mixed with the explosive material, the proportion inwhich these materials are present depending upon the amount of water ofcrystallization contained by the temperature reducing material. and uponthe extent of the reduction desired. \Yilh materials holding largeamounts of water of ervstallization, the amount of the temperatureredueing agent present in the explosive may be roughly 3% to 25%, whilewith ma- 'ter1als holding small'amounts of Water of crystallization theamount of the reducing material pres-nt may be to 40%. As specitieexamples. I may form my explosive of 80% explosive base if gypsum isemployed l may have 30% of this material with i()% of explosive base. Inany event, enough of the cooling agent and ulexi't/e; 01'' should beadded to insure the presence in -the explosive of 3% to 20% of availablewater. and for coal mining purposes sufficient material should be addedto bring the flame temperature of the explosive below 2200 C. andpreferably below 2000 C.

Where in the claims I employ the terms materials or salts containingwater, I refer to water contained or held in such a form as to be availahle for the purpose described, such as water of crystallization, orwater of constitution.

1. An explosive mixture comprising a nitrate explosive base associatedwith a water-containing water-insoluble borate.

2. An explosive mixture comprising a nitrate explosive base associatedwith a hydrous calcium borate.

3. An explosive mixture comprising a nitrate explosive base associatedwith ulexite,

said ulexit-e constituting 3% to of the mixture.

WALTER O. SNELLIHG.

